Steve Werner suspected his health was in trouble even before his golden retriever, Wrigley, started sniffing around.

His symptoms were vague back in June - occasional ringing in his ears, a general feeling of unease. His doctor couldn't pinpoint a problem. Tests came back negative.

Then in July, Wrigley started to behave strangely.

Every day when Werner would curl up next to his beloved canine at his Brentwood home, she would turn, focus on his right ear and sniff doggedly.

"I thought it was just a friendly sniff," Werner said. "But after four or five days, I realized she seemed to be focusing on something. At some point, I noticed she was always sniffing at the opening of my right ear. She would set herself up and intently smell my ear."

One day, Werner was watching TV when a feature about cancer-sniffing dogs grabbed his attention. What he heard propelled him back to his doctor's office.

An MRI of Werner's head revealed a brain tumor the size of a pingpong ball that had spread into the inner canal of Werner's right ear - the very ear Wrigley had been sniffing persistently.

Werner, 40, had a rare nonmalignant tumor called acoustic schwannoma. If not caught in time, it could have caused a stroke or permanent facial paralysis.

He underwent surgery in Los Angeles in February to remove it and has been recuperating at home.

Doggy diagnosis

Because of their keen sense of smell, canines have long been used to sniff out guns, bombs, cadavers and illegal drugs, among other things.

Dogs also have been trained in medical settings to detect impending epileptic seizures or identify tuberculosis in undiagnosed patients.

Now, researchers are studying the effectiveness of dogs in detecting cancer.

"A couple preliminary studies suggest that a dog's nose is extremely sensitive at detecting certain chemicals that make up the constituents of a cancer cell," said Dr. Ted Gansler, director of medical content in health information for the American Cancer Society. "But it's hard to know how accurate untrained dogs are."

Research suggests that cancer cells emit chemicals not found in healthy tissue. Certain types of solid tumors of the breast, prostate, lung and bladder have been found to discharge volatile or aerosolized compounds such as formaldehyde, benzene and alkanes.

Some researchers have successfully trained dogs to identify the distinctive smells of the chemicals.

A study in the British Medical Journal in 2004 concluded that dogs could be trained to detect bladder cancer on the basis of urine odor alone.

Different breeds have been trained, depending on the study, including poodles, beagles, cocker spaniels, Labrador retrievers, Portuguese water dogs and mutts.

Nicholas Broffman, executive director of the Pine Street Foundation in California, which published a study on cancer-detecting dogs last month, found the Wrigley tale intriguing.

"That's a very common story," he said. "That's one of the reasons we did this research, because we've heard all these stories and we wanted to do a double-blind study to test the idea."

The foundation is a nonprofit, independent cancer research and education organization. In its study published in a cancer journal, researchers collected breath samples in plastic tubes from 83 healthy volunteers, 55 lung cancer patients and 31 breast cancer patients.

The tubes were numbered and placed in plastic boxes and presented to the dogs, five at a time. If the dog detected cancer, it was trained to sit or lie down. Researchers determined that the dogs were accurate 99 percent of the time in detecting lung cancer and 88 percent of the time in detecting breast cancer.

The breath samples were "blinded" so neither dog handlers nor observers knew which samples were being tested until the study was completed.

"We set out to see if cancer has a smell and if people with cancer have a different smell than people without cancer," Broffman said. "We were impressed with how well the dogs did."

Broffman said it's not clear whether dogs can detect both malignant and benign tumors, such as the one Werner had.

"We're not sure exactly what the dogs are smelling, although we have a hunch," Broffman said. "We want to do additional research to study what the compounds are that they are responding to."

Some cancers, such as ovarian and pancreatic cancer, are usually not caught until quite advanced, and "if there is a possibility of detecting either one at stage one, this could be revolutionary," he said.

'Many steps away'

Not everyone is wagging their tails about the dog studies.

The results of the lung and breast cancer study were too good to be true, said Donald Berry, chairman of the department of applied biostatistics and applied mathematics at the University of Texas-M.D. Anderson Cancer Center in Houston.

"It's essentially impossible that anything could be that good," he said.

Berry also discounted the idea that cancers smell. "If they do, they are bound to smell different," he said, because there are so many different types.

Screening in actual clinical practice is more difficult than the situation the dogs were encountering, said Gansler of the cancer society.

In the published studies, dogs were taught to distinguish between normal samples and samples taken from people with cancer. But samples from people with a variety of other kinds of disease weren't included, Gansler said.

"So we don't know very much about the potential for false positive results from the dogs in which they are confusing, say, lung cancer and pneumonia, or urinary infection and bladder cancer."

"This research is a good first step, but still many steps away from actual clinical use," he said.

No one expects dogs to replace biopsies, X-rays or other cancer-screening tools, but researchers are intrigued by the possibilities in the olfactory abilities of man's best friend.

Dogs could possibly be used to help identify chemicals associated with cancer, which would aid scientists in developing tests, possibly a breathalyzer, to detect specific compounds.

Werner, meanwhile, is coping with temporary paralysis on the right side of his face as he recovers. The surgery also caused complete hearing loss in his right ear. He is grateful the tumor was caught when it was.

"Don't get me wrong, I give credit to my doctor; she was the one who found it," he said. "But there isn't any doubt in my mind that my dog was looking out for me, that the unconditional love I gave her came back."

Wrigley's life is much like it was before she morphed into Doctor Dog.

She spends much of her days watching the comings and goings on her block. Friends and neighbors who organized meals for Werner during his recuperation included special treats for the laid-back pet. She turned 11 in July.

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I'd heard about dogs sniffing out bladder cancer before, but this is also fascinating.

Ultimately it's a bit useless IMO. I mean we could screen everyone with a CT for cancer routinely but for the amount of positive results we'd get it's not really worth it, not to mention the cost. The only sensible way of doing things is to scan someone if they show symptoms, which is often too late.

The same principal applies here; dogs can smell cancer, great. What are you going to do, get everyone to go the doctors for a routine sniff? I suppose it's cheaper than a CT...

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I'd heard about dogs sniffing out bladder cancer before, but this is also fascinating.

Ultimately it's a bit useless IMO. I mean we could screen everyone with a CT for cancer routinely but for the amount of positive results we'd get it's not really worth it, not to mention the cost. The only sensible way of doing things is to scan someone if they show symptoms, which is often too late.

The same principal applies here; dogs can smell cancer, great. What are you going to do, get everyone to go the doctors for a routine sniff? I suppose it's cheaper than a CT...